1. Technical Field
Embodiments of the present disclosure may generally relate to a semiconductor device, semiconductor system, and method related to performing a refresh operation.
2. Related Art
A semiconductor device includes a plurality of cell arrays for storing data. Each of the plurality of cell arrays includes a plurality of cells. Each cell is constructed by a cell capacitor and a cell transistor. The semiconductor device stores data through an operation of charging or discharging electric charges to or from the cell capacitor. Ideally, the amount of electric charges stored in the cell capacitor should be always constant. However, the amount of electric charges stored in the cell capacitor, actually, varies due to a voltage difference with respect to a peripheral circuit. Electric charges may leak in the state in which the cell capacitor is charged, or electric charges may be introduced in the state in which the cell capacitor is discharged. The variation in the amount of electric charges in the cell capacitor means that data stored in the cell capacitor is changed, that is, loss of stored data. A semiconductor device performs a refresh operation to prevent a phenomenon whereby data is lost as described above.
As processing technologies are developed, the degree of integration of a semiconductor device is gradually increased. An increase in the degree of integration of a semiconductor device exerts an influence on the size of a bank. The fact that the size of a bank is gradually decreased means that the interval between cells decreases, which means that the interval between word lines respectively coupled to adjacent cells decreases. While a particular problem has not occurred so far in relation with the interval between word lines, new issues which have not been previously considered to be problematic are caused recently as the interval between word lines decreases. One of the issues is an interference effect that occurs between adjacent word lines. If an interference effect occurs between adjacent word lines, the cells coupled to the corresponding word lines may be difficult to retain data stored therein. That is, the probability of losing data increases.
Recently, in a semiconductor device, in order to prevent data from being lost, a refresh operation is performed for all the cells of a bank, or an additional refresh operation is performed for adjacent word lines adjacent to a target word line which is accessed concentratedly.